The drill bit of the present invention will be employed in drilling in various types of rock, such as variations from limestone to clay shale. Vibrations in the drill bit occur due to variations in the friction between the drill bit and the bore hole wall/bottom, and are modulated by the mass of the drill bit, weight on bit, torsion on bit, as well as by interaction with the drill string. Such vibrations in the shape of rapidly shifting torsion momentum on the drill bit will propagate over to the drill string, and are undesired.
A so-called PDC-drill bit comprises a forged steel crown with an upper hollow conical pin connector connectable to the lower module of a drill string, The drill string is a tool, more or less cylindrical, hollow with a central channel for bore fluid to nozzles in the crown, where the crown normally comprises wings with cylindrical-shaped PDC-cutters fixed on top of the wings. The PDC-cutters lean forward in order for parts of the front surface to scratch frontally against the bottom of the bore hole, cutting out a similar shallow circular recess. The bore fluid nozzles end in the recesses between the wings, and wash away the residue and cool down the PDC-cutters. The PDC-cutters can be solded or welded into cylindrical recesses in the drill bit. The drill bit can be equipped with a string fixed into a cylindrical breaker slot with a hollow upper pin connector.
The crown itself, underneath the cylindrical, hollow string, can be a so-called matrix bit made out of a pressed, sintered ceramical/metallic powder material, where the PDC-cutters are fixed to the pressed matrix. Then will the drill bit be equipped with a string fixed into a cylindrical breaker slot with a hollow upper pin connector.
U.S. Pat. No. 8,261,632B2 describes methods of forming bit-bodies for earth-boring bits including assembling and sintering of green components that have been infiltrated, brown components that have been infiltrated, or fully sintered components that have been infiltrated.
Other methods include isostatically pressing a powder to form a green body substantially composed of a particle-matrix composite material, and sintering or hot isostatic pressing the green body or the brown body to provide a bit body having a desired final density.
Methods of forming earth-boring bits include providing a bit body substantially formed of a particle-matrix composite material and attaching a shank to the body.
The body is provided by pressing a powder to form a green body and sintering the green body.
U.S. Pat. No. 6,102,142A describes a drilling tool including a drilling head equipped with cutting edges and fitted with several shock-absorption elements, of which at least one part is made of an elastomer material. Each shock-absorption element having a block incorporating one portion inserted inside a receptor housing formed on the tool surface, and a portion which projects outward beyond the receptor housing.